Aircraft: LARGE TRANSPORT; LOW WING; 2 TURBOJET ENG
Phase of flight: Final Approach
Anomaly: Deviation - Speed All Types; Deviation / Discrepancy - Procedural Clearance

While flying the SEAVU 2 Arrival procedure into LAX; we were instructed by SoCal Approach to delete the speed restriction at KONZL (280 KIAS) and 'Maintain 310 knots or greater.' We continued the profile descent at 320 KIAS until advised to 'Maintain 250 knots at LUVYN' (39 NM from RNWY 25L @ 10;000 feet). Approximately 10 miles later we were instructed to 'Maintain 210 knots or greater at GAATE.' (15.2 NM from LAX RWY 25L @ 5;000). As the speeds directed by ATC were far higher than the normal profile; and with the aircraft clean/nose down (an energy/speed building attitude) we were forced to begin deceleration to arrive at GAATE @ 210 KIAS plus; and still be able to further slow and configure the aircraft for the ILS approach to 25L (the airport was IMC at the time). As we passed trough 230 KIAS the SoCal Controller called us testily and demanded our airspeed. We reported '230 knots' to which he angrily replied; 'I told you to maintain 250 knots; and you're not the only one out there.' This was in direct conflict with his previous clearance to 'Maintain 210 knots or greater at GAATE.' Which obviously required deceleration to comply and still be able to safely configure for the ILS approach. We temporarily increased speed back to 250 KIAS for approximately 2 minutes after which we had to rapidly decelerate again in order to be able to start extending flaps; slowing and configuring for the final portion of the IFR approach procedure to LAX RWY 25L. The effect of the controller directing higher than normal arrival speeds deep into the arrival; as well as his conflicting and unrealistic demands approaching GAATE; left us with an extremely challenging series of transitions from a high speed descent/arrival to a rushed deceleration; descent and configuration into a hard IFR approach at the last minute. In fact; aircraft auto flight systems were unable to perform the abrupt/conflicting speed deviations directed by ATC requiring the aircraft to be uncoupled from the autopilot and hand flown for the remainder of the ILS approach to a successful landing. Poor ATC communication/conflicting clearances during this arrival created a highly compressed and artificially complex series of events during which the flight crew was forced to scramble to operate the aircraft safely and in accordance with SOP/procedures. Far more situational awareness. Explanation and intent from ATC controllers. In this instance; Controller gave conflicting clearances; abandoned professional standards of language/comm and directed aircrew to operate the aircraft in a manner that clearly demonstrated ignorance of physics or performance capabilities within an IFR/IMC environment. While descending via the SEAVU2 arrival into LAX we were instructed to maintain 250 knots. Then we received further clearance to maintain 210 knots or greater at GAATE. We began to slow in accordance with instruction and at about 230 knots the Controller asked our speed; which we responded 230 knots. The Controller then said; 'I told you to maintain 250 knots; and you're not the only one out there.' We then increased speed to 250 knots until approaching GAATE at which time we used gear; full speed brakes; and flaps to slow to be stabilized for the approach. Having flown this approach many times in the past where slowing far out on the approach is typical; the instructions to maintain 210 or greater at GAATE seemed faster then normal. After flying this approach; and complying with the '210 or greater at GAATE'; I can say; it's a bad idea. It causes the aircrew to be rushed; and is very difficult to slow to achieve a stable approach; especially with the winglet aircraft that do not; 'Go down; slow down'; well. Pilots report of a flight into LAX in which the Controller assigned one speed then told the pilots they were going too slow. Pilots had to scramble to keep aircraft fast into the airport.